1. The highest point (of something)
   "at the apex of the pyramid";
   - vertex, peak, acme
    
2. The point on the celestial sphere toward which the sun and solar system appear to be moving relative to the fixed stars
   "Astronomers use the solar apex to understand the sun's movement through space";
   - solar apex, apex of the sun's way

Derived forms: apexes, apices

Type of: celestial point, extreme, extreme point, extremum

Antonym: antapex

Part of: celestial sphere, empyrean, firmament, heavens, sphere, vault of heaven, welkin

Encyclopedia: Apex, Nevada